The present invention relates to a method for fabricating a semiconductor package, and more particularly to a method for fabricating a semiconductor package capable of implementing fine pitch.
The semiconductor package uses a soldering manner through the use of a lead frame as a method to mount a semiconductor chip on an external circuit. However, although the soldering manner through the use of the lead frame has advantages of easiness in process progress and excellence in reliability, it also has a disadvantage related to electrical characteristics because of the length of the transfer of the electrical signal between the semiconductor chip and the external circuit.
In order to solve such a problem, it has been proposed to package a flip chip package at a high density. The flip chip package is created by disposing electrically connectable material, such as a bump, between bonding pads of the semiconductor chip and connecting pads of the substrate.
FIG. 1 is a cross-sectional view showing a flip chip package having a conventional bump.
For example, the prior art introduces a flip chip package that is formed by attaching a semiconductor chip 100 provided with a plurality of bonding pads 102 on a substrate 120 provided with connecting pads 122 by using a solder bump 154. The solder bump 154 is disposed between the bonding pads 102 and the connecting pads 122 to electrically and physically connect the semiconductor chip to the substrate 120.
In FIG. 1, the reference numerals 124 represents a ball land, 130 represents a solder ball, 140 represents an encapsulant, and 150 represents a filler.
Since the flip chip package has a short electrical signal path, the resistance is reduced so that it has excellent electrical characteristics in that the power required can be reduced and the operation speed of the semiconductor package can be improved. Since the rear surface of the semiconductor chip is exposed to the external circuit, the thermal characteristics of the semiconductor chip are excellent. This makes it possible to implement the semiconductor package with reduced thickness.
However, the conventional flip chip package should form a filler in order to protect the electrical connecting portion between the semiconductor chip and the substrate by a solder bump, and that process becomes complicated. Since the solder bump generally used in the flip ship package is formed in a circle, it is difficult to implement fine pitch, and if the solder bump shape is formed below a predetermined size in order to form the fine pitch, the reliability of a joint unit deteriorates.